(From company literature) Tamrac 5273 Expedition 3. The Expedition 3 offers expedition-level performance in a compact photo backpack. This full-featured pack is perfect for holding most SLRs with a lens attached up to 7" long, 3-4 additional lenses and accessories. For maximum protection, the pack is fully padded with thick, closed-cell foam. A cinch strap keeps the camera in place while a large rain flap protects the main compartment zippers. Features include: QuickClip™ tripod attachment system with vinyl reinforced mesh pocket, front accessory pocket with Tamrac's U.S. patented Memory & Battery Management System™ that uses red flags to identify which memory cards and batteries are available and which ones are used up, EasyGrip™ handle, inner Windowpane-Mesh™ accessory pockets, and padded backpack harness. Add Tamrac accessories to the Strap Accessory System™ (S.A.S™) and Modular Accessory System™ (M.A.S.™) attachment slots to customize this pack.

Specifications:

Type: Backpack

Available Colors: Black

Outer Fabric: Unspecified

Type of Closure: Weather resistant zipper

Capacity: 1 digital or film SLR with lens attached up to 7 inch long, 3-4 additional lenses and accessories

I carry an olympus E500, with attached 14-54/2.8-3.5, 50-200/2.8-3.5 on one side, and FL36 on the other side. After this I am left with small space to fit the EC14 and EX25. Along with the flash I can squeeze in a polariser. The front pockets and the inside pockets carry the 2 extra blm-01 battery, 3-4 AA battery, 3-4 CF cards, 1-2 manuals or documents (I carry DOF charts).

If this is the equipment you want to carry, this is the bag for you, otherwise search a bigger one. I use it for one day shooting or specific places where I only need 2 lenses. For more gear I use the mountainsmith Quantum and I like it very much.